2021-01-13 14:07:35 +01:00
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/*
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* mm-naive.c - The fastest, least memory-efficient malloc package.
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*
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* In this naive approach, a block is allocated by simply incrementing
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* the brk pointer. A block is pure payload. There are no headers or
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* footers. Blocks are never coalesced or reused. Realloc is
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* implemented directly using mm_malloc and mm_free.
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*
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* NOTE TO STUDENTS: Replace this header comment with your own header
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* comment that gives a high level description of your solution.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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#include <unistd.h>
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#include <string.h>
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#include "mm.h"
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#include "memlib.h"
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/*********************************************************
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* NOTE TO STUDENTS: Before you do anything else, please
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* provide your team information in the following struct.
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********************************************************/
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team_t team = {
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/* Team name */
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"anna.schlittenhardt@stud.uni-due.de+tuan-dat.tran@stud.uni-due.de",
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/* First member's full name */
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"Anna Schlittenhardt",
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/* First member's email address */
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"anna.schlittenhardt@stud.uni-due.de",
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/* Second member's full name (leave blank if none) */
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"Tuan-Dat Tran",
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/* Second member's email address (leave blank if none) */
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"tuan-dat.tran@stud.uni-due.de"
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};
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2021-01-24 16:35:51 +01:00
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2021-01-24 13:55:21 +01:00
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////////////////////////////////////////////////////////////////////////////////
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/////////////////////////////////// STRUCTURE //////////////////////////////////
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////////////////////////////////////////////////////////////////////////////////
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// Filled Blk
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// 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
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// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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// HEADER | SIZE | A|
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// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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2021-01-24 16:35:51 +01:00
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// BP-> | ALLOCED MEMORY |
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2021-01-24 13:55:21 +01:00
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// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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// FOOTER | SIZE | A|
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// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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//
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// Empty Blk
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// 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
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// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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// HEADER | SIZE | A|
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// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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2021-01-24 16:35:51 +01:00
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// BP-> | PTR TO PREV FREE BLK |
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2021-01-24 13:55:21 +01:00
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// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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// | PTR TO NEXT FREE BLK |
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// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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2021-01-24 16:35:51 +01:00
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// | UNALLOC MEMORY |
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2021-01-24 13:55:21 +01:00
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// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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// FOOTER | SIZE | A|
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// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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////////////////////////////////////////////////////////////////////////////////
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//////////////////////////////////// DEFINES ///////////////////////////////////
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////////////////////////////////////////////////////////////////////////////////
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2021-01-13 14:07:35 +01:00
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/* single word (4) or double word (8) alignment */
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#define ALIGNMENT 8
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/* rounds up to the nearest multiple of ALIGNMENT */
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#define ALIGN(size) (((size) + (ALIGNMENT-1)) & ~0x7)
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#define SIZE_T_SIZE (ALIGN(sizeof(size_t)))
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2021-01-14 15:30:36 +01:00
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/* Page 830, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */
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/* Basic constants and macros */
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#define WSIZE 4 /* Word and header/footer size (bytes) */
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#define DSIZE 8 /* Double word size (bytes) */
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#define CHUNKSIZE (1<<12) /* Extend heap by this amount (bytes) */
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#define MAX(x, y) ((x) > (y)? (x) : (y))
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2021-01-24 16:35:51 +01:00
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#define MIN(x, y) ((x) < (y)? (x) : (y))
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2021-01-14 15:30:36 +01:00
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/* Pack a size and allocated bit into a word */
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#define PACK(size, alloc) ((size) | (alloc))
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/* Read and write a word at address p */
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#define GET(p) (*(unsigned int *)(p))
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#define PUT(p, val) (*(unsigned int *)(p) = (val))
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2021-01-24 20:23:57 +01:00
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#define PUTT(p, val) (*(unsigned int *)(p) = (val))
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2021-01-14 15:30:36 +01:00
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/* Read the size and allocated fields from address p */
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#define GET_SIZE(p) (GET(p) & ~0x7)
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#define GET_ALLOC(p) (GET(p) & 0x1)
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/* Given block ptr bp, compute address of its header and footer */
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#define HDRP(bp) ((char *)(bp) - WSIZE)
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#define FTRP(bp) ((char *)(bp) + GET_SIZE(HDRP(bp)) - DSIZE)
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/* Given block ptr bp, compute address of next and previous blocks */
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#define NEXT_BLKP(bp) ((char *)(bp) + GET_SIZE(((char *)(bp) - WSIZE)))
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#define PREV_BLKP(bp) ((char *)(bp) - GET_SIZE(((char *)(bp) - DSIZE)))
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2021-01-24 16:35:51 +01:00
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#define PUT_PTR(p, ptr) (*(unsigned int *)(p) = (unsigned int)(ptr))
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2021-01-24 19:40:08 +01:00
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#define PRV_PTR(ptr) ((char *)(ptr))
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#define NXT_PTR(ptr) ((char *)(ptr) + WSIZE)
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#define PRV_BLK(ptr) (*(char **)(ptr))
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#define NXT_BLK(ptr) (*(char **)(NXT_PTR(ptr)))
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2021-01-24 16:35:51 +01:00
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2021-01-24 13:55:21 +01:00
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////////////////////////////////////////////////////////////////////////////////
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2021-01-24 19:40:08 +01:00
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////////////////////////////////// GLOBAL VARS /////////////////////////////////
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2021-01-24 13:55:21 +01:00
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////////////////////////////////////////////////////////////////////////////////
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2021-01-24 19:40:08 +01:00
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#define LISTSIZE 20
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2021-01-24 13:55:21 +01:00
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static char* heap_listp;
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2021-01-24 16:35:51 +01:00
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char* seg_list[LISTSIZE];
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2021-01-14 15:30:36 +01:00
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2021-01-24 13:55:21 +01:00
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////////////////////////////////////////////////////////////////////////////////
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///////////////////////////////// HELPER PREDEF ////////////////////////////////
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////////////////////////////////////////////////////////////////////////////////
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2021-01-14 15:30:36 +01:00
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/* Page 856-858, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */
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2021-01-24 20:23:57 +01:00
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static void* place(void *bp, size_t asize);
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2021-01-24 13:55:21 +01:00
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/* Page 833, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */
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static void* coalesce(void *bp);
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/* Page 831, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */
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static void* extend_heap(size_t words);
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2021-01-24 19:40:08 +01:00
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static void add_free(void* bp, size_t asize);
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2021-01-24 13:55:21 +01:00
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////////////////////////////////////////////////////////////////////////////////
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/////////////////////////////// HELPER FUNCTIONS ///////////////////////////////
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////////////////////////////////////////////////////////////////////////////////
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2021-01-24 20:23:57 +01:00
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static void *extend_heap(size_t size)
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2021-01-24 18:08:02 +01:00
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{
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2021-01-24 20:23:57 +01:00
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void *ptr;
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size_t asize; // Adjusted size
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asize = ALIGN(size);
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if ((ptr = mem_sbrk(asize)) == (void *)-1)
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return NULL;
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// Set headers and footer
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PUTT(HDRP(ptr), PACK(asize, 0));
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PUTT(FTRP(ptr), PACK(asize, 0));
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PUTT(HDRP(NEXT_BLKP(ptr)), PACK(0, 1));
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add_free(ptr, asize);
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return coalesce(ptr);
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2021-01-24 18:08:02 +01:00
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}
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2021-01-24 20:23:57 +01:00
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static void add_free(void *ptr, size_t size) {
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int list = 0;
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void *search_ptr = ptr;
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void *insert_ptr = NULL;
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// Select segregated list
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while ((list < LISTSIZE - 1) && (size > 1)) {
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size >>= 1;
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list++;
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2021-01-14 15:30:36 +01:00
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}
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2021-01-24 20:23:57 +01:00
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// Keep size ascending order and search
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search_ptr = seg_list[list];
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while ((search_ptr != NULL) && (size > GET_SIZE(HDRP(search_ptr)))) {
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insert_ptr = search_ptr;
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search_ptr = PRV_BLK(search_ptr);
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2021-01-14 15:30:36 +01:00
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}
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2021-01-24 20:23:57 +01:00
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// Set predecessor and successor
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if (search_ptr != NULL) {
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if (insert_ptr != NULL) {
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PUT_PTR(PRV_PTR(ptr), search_ptr);
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PUT_PTR(NXT_PTR(search_ptr), ptr);
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PUT_PTR(NXT_PTR(ptr), insert_ptr);
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PUT_PTR(PRV_PTR(insert_ptr), ptr);
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} else {
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PUT_PTR(PRV_PTR(ptr), search_ptr);
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PUT_PTR(NXT_PTR(search_ptr), ptr);
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PUT_PTR(NXT_PTR(ptr), NULL);
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seg_list[list] = ptr;
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}
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} else {
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if (insert_ptr != NULL) {
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PUT_PTR(PRV_PTR(ptr), NULL);
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PUT_PTR(NXT_PTR(ptr), insert_ptr);
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PUT_PTR(PRV_PTR(insert_ptr), ptr);
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} else {
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PUT_PTR(PRV_PTR(ptr), NULL);
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PUT_PTR(NXT_PTR(ptr), NULL);
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seg_list[list] = ptr;
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}
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2021-01-24 19:40:08 +01:00
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}
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2021-01-24 20:23:57 +01:00
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return;
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2021-01-24 19:40:08 +01:00
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}
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2021-01-24 19:52:07 +01:00
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2021-01-24 20:23:57 +01:00
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static void delete_node(void *ptr) {
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int list = 0;
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size_t size = GET_SIZE(HDRP(ptr));
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// Select segregated list
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while ((list < LISTSIZE - 1) && (size > 1)) {
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size >>= 1;
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list++;
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}
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if (PRV_BLK(ptr) != NULL) {
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if (NXT_BLK(ptr) != NULL) {
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PUT_PTR(NXT_PTR(PRV_BLK(ptr)), NXT_BLK(ptr));
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PUT_PTR(PRV_PTR(NXT_BLK(ptr)), PRV_BLK(ptr));
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} else {
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PUT_PTR(NXT_PTR(PRV_BLK(ptr)), NULL);
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seg_list[list] = PRV_BLK(ptr);
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2021-01-24 16:35:51 +01:00
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}
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2021-01-24 20:23:57 +01:00
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} else {
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if (NXT_BLK(ptr) != NULL) {
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PUT_PTR(PRV_PTR(NXT_BLK(ptr)), NULL);
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2021-01-24 16:35:51 +01:00
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} else {
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2021-01-24 20:23:57 +01:00
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seg_list[list] = NULL;
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2021-01-24 16:35:51 +01:00
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}
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}
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2021-01-24 20:23:57 +01:00
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return;
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2021-01-14 15:30:36 +01:00
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}
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2021-01-24 20:23:57 +01:00
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static void *coalesce(void *ptr)
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2021-01-14 15:30:36 +01:00
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{
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2021-01-24 20:23:57 +01:00
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size_t prev_alloc = GET_ALLOC(HDRP(PREV_BLKP(ptr)));
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size_t next_alloc = GET_ALLOC(HDRP(NEXT_BLKP(ptr)));
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size_t size = GET_SIZE(HDRP(ptr));
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2021-01-14 15:30:36 +01:00
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2021-01-24 20:23:57 +01:00
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if (prev_alloc && next_alloc) { // Case 1
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return ptr;
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}
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else if (prev_alloc && !next_alloc) { // Case 2
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delete_node(ptr);
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delete_node(NEXT_BLKP(ptr));
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size += GET_SIZE(HDRP(NEXT_BLKP(ptr)));
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PUT(HDRP(ptr), PACK(size, 0));
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PUT(FTRP(ptr), PACK(size, 0));
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} else if (!prev_alloc && next_alloc) { // Case 3
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delete_node(ptr);
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delete_node(PREV_BLKP(ptr));
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size += GET_SIZE(HDRP(PREV_BLKP(ptr)));
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PUT(FTRP(ptr), PACK(size, 0));
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PUT(HDRP(PREV_BLKP(ptr)), PACK(size, 0));
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ptr = PREV_BLKP(ptr);
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} else { // Case 4
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|
|
|
delete_node(ptr);
|
|
|
|
|
delete_node(PREV_BLKP(ptr));
|
|
|
|
|
delete_node(NEXT_BLKP(ptr));
|
|
|
|
|
size += GET_SIZE(HDRP(PREV_BLKP(ptr))) + GET_SIZE(HDRP(NEXT_BLKP(ptr)));
|
|
|
|
|
PUT(HDRP(PREV_BLKP(ptr)), PACK(size, 0));
|
|
|
|
|
PUT(FTRP(NEXT_BLKP(ptr)), PACK(size, 0));
|
|
|
|
|
ptr = PREV_BLKP(ptr);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
add_free(ptr, size);
|
|
|
|
|
|
|
|
|
|
return ptr;
|
|
|
|
|
}
|
2021-01-24 16:35:51 +01:00
|
|
|
|
|
2021-01-24 20:23:57 +01:00
|
|
|
|
static void *place(void *ptr, size_t asize)
|
|
|
|
|
{
|
|
|
|
|
size_t ptr_size = GET_SIZE(HDRP(ptr));
|
|
|
|
|
size_t remainder = ptr_size - asize;
|
|
|
|
|
|
|
|
|
|
delete_node(ptr);
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
if (remainder <= DSIZE * 2) {
|
|
|
|
|
// Do not split block
|
|
|
|
|
PUT(HDRP(ptr), PACK(ptr_size, 1));
|
|
|
|
|
PUT(FTRP(ptr), PACK(ptr_size, 1));
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
else if (asize >= 100) {
|
|
|
|
|
// Split block
|
|
|
|
|
PUT(HDRP(ptr), PACK(remainder, 0));
|
|
|
|
|
PUT(FTRP(ptr), PACK(remainder, 0));
|
|
|
|
|
PUTT(HDRP(NEXT_BLKP(ptr)), PACK(asize, 1));
|
|
|
|
|
PUTT(FTRP(NEXT_BLKP(ptr)), PACK(asize, 1));
|
|
|
|
|
add_free(ptr, remainder);
|
|
|
|
|
return NEXT_BLKP(ptr);
|
|
|
|
|
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
else {
|
|
|
|
|
// Split block
|
|
|
|
|
PUT(HDRP(ptr), PACK(asize, 1));
|
|
|
|
|
PUT(FTRP(ptr), PACK(asize, 1));
|
|
|
|
|
PUTT(HDRP(NEXT_BLKP(ptr)), PACK(remainder, 0));
|
|
|
|
|
PUTT(FTRP(NEXT_BLKP(ptr)), PACK(remainder, 0));
|
|
|
|
|
add_free(NEXT_BLKP(ptr), remainder);
|
|
|
|
|
}
|
|
|
|
|
return ptr;
|
2021-01-14 15:30:36 +01:00
|
|
|
|
}
|
|
|
|
|
|
2021-01-24 13:55:21 +01:00
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
|
|
|
////////////////////////////// MAIN FUNCTIONALITY //////////////////////////////
|
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
2021-01-14 15:30:36 +01:00
|
|
|
|
/* Page 831, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */
|
2021-01-13 14:07:35 +01:00
|
|
|
|
/*
|
|
|
|
|
* mm_init - initialize the malloc package.
|
|
|
|
|
*/
|
|
|
|
|
int mm_init(void)
|
|
|
|
|
{
|
2021-01-24 16:35:51 +01:00
|
|
|
|
// init seg_list
|
|
|
|
|
for (size_t i = 0; i < LISTSIZE; ++i) {
|
2021-01-24 13:55:21 +01:00
|
|
|
|
seg_list[i] = NULL;
|
|
|
|
|
}
|
2021-01-24 16:35:51 +01:00
|
|
|
|
|
2021-01-14 15:30:36 +01:00
|
|
|
|
/* Create the initial empty heap */
|
|
|
|
|
if ((heap_listp = mem_sbrk(4*WSIZE)) == (void *)-1)
|
|
|
|
|
return -1;
|
|
|
|
|
PUT(heap_listp, 0); /* Alignment padding */
|
|
|
|
|
PUT(heap_listp + (1*WSIZE), PACK(DSIZE, 1)); /* Prologue header */
|
|
|
|
|
PUT(heap_listp + (2*WSIZE), PACK(DSIZE, 1)); /* Prologue footer */
|
|
|
|
|
PUT(heap_listp + (3*WSIZE), PACK(0, 1)); /* Epilogue header */
|
|
|
|
|
heap_listp += (2*WSIZE);
|
|
|
|
|
|
|
|
|
|
/* Extend the empty heap with a free block of CHUNKSIZE bytes */
|
|
|
|
|
if (extend_heap(CHUNKSIZE/WSIZE) == NULL)
|
|
|
|
|
return -1;
|
2021-01-13 14:07:35 +01:00
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
2021-01-14 15:30:36 +01:00
|
|
|
|
/* Page 834, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */
|
2021-01-13 14:07:35 +01:00
|
|
|
|
/*
|
|
|
|
|
* mm_malloc - Allocate a block by incrementing the brk pointer.
|
|
|
|
|
* Always allocate a block whose size is a multiple of the alignment.
|
|
|
|
|
*/
|
|
|
|
|
void *mm_malloc(size_t size)
|
|
|
|
|
{
|
2021-01-24 20:23:57 +01:00
|
|
|
|
size_t asize; /* Adjusted block size */
|
2021-01-14 15:30:36 +01:00
|
|
|
|
size_t extendsize; /* Amount to extend heap if no fit */
|
2021-01-24 20:23:57 +01:00
|
|
|
|
void *ptr = NULL; /* Pointer */
|
|
|
|
|
|
|
|
|
|
// Ignore size 0 cases
|
2021-01-14 15:30:36 +01:00
|
|
|
|
if (size == 0)
|
2021-01-13 14:07:35 +01:00
|
|
|
|
return NULL;
|
2021-01-24 20:23:57 +01:00
|
|
|
|
|
|
|
|
|
// Align block size
|
|
|
|
|
if (size <= DSIZE) {
|
|
|
|
|
asize = 2 * DSIZE;
|
|
|
|
|
} else {
|
2021-01-24 16:35:51 +01:00
|
|
|
|
asize = ALIGN(size+DSIZE);
|
2021-01-13 14:07:35 +01:00
|
|
|
|
}
|
2021-01-24 20:23:57 +01:00
|
|
|
|
|
|
|
|
|
int list = 0;
|
|
|
|
|
size_t searchsize = asize;
|
|
|
|
|
// Search for free block in segregated list
|
|
|
|
|
while (list < LISTSIZE) {
|
|
|
|
|
if ((list == LISTSIZE- 1) || ((searchsize <= 1) && (seg_list[list] != NULL))) {
|
|
|
|
|
ptr = seg_list[list];
|
|
|
|
|
// Ignore blocks that are too small or marked with the reallocation bit
|
|
|
|
|
while ((ptr != NULL) && (asize > GET_SIZE(HDRP(ptr))))
|
|
|
|
|
{
|
|
|
|
|
ptr = PRV_BLK(ptr);
|
|
|
|
|
}
|
|
|
|
|
if (ptr != NULL)
|
|
|
|
|
break;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
searchsize >>= 1;
|
|
|
|
|
list++;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// if free block is not found, extend the heap
|
|
|
|
|
if (ptr == NULL) {
|
|
|
|
|
extendsize = MAX(asize, CHUNKSIZE);
|
|
|
|
|
|
|
|
|
|
if ((ptr = extend_heap(extendsize)) == NULL)
|
|
|
|
|
return NULL;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// Place and divide block
|
|
|
|
|
ptr = place(ptr, asize);
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
// Return pointer to newly allocated block
|
|
|
|
|
return ptr;
|
2021-01-13 14:07:35 +01:00
|
|
|
|
}
|
|
|
|
|
|
2021-01-14 15:30:36 +01:00
|
|
|
|
/* Page 833, Pearson R. Bryant – D. O’Hallaron. Computer Systems: A Programmer’s Perspective.3rd Edition, Pearson, 2003. */
|
2021-01-13 14:07:35 +01:00
|
|
|
|
/*
|
|
|
|
|
* mm_free - Freeing a block does nothing.
|
|
|
|
|
*/
|
|
|
|
|
void mm_free(void *ptr)
|
|
|
|
|
{
|
2021-01-24 16:35:51 +01:00
|
|
|
|
size_t size = GET_SIZE(HDRP(ptr));
|
2021-01-24 18:08:02 +01:00
|
|
|
|
add_free(ptr, size);
|
2021-01-14 15:30:36 +01:00
|
|
|
|
PUT(HDRP(ptr), PACK(size, 0));
|
|
|
|
|
PUT(FTRP(ptr), PACK(size, 0));
|
2021-01-24 16:35:51 +01:00
|
|
|
|
|
2021-01-14 15:30:36 +01:00
|
|
|
|
coalesce(ptr);
|
2021-01-13 14:07:35 +01:00
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* mm_realloc - Implemented simply in terms of mm_malloc and mm_free
|
|
|
|
|
*/
|
|
|
|
|
void *mm_realloc(void *ptr, size_t size)
|
|
|
|
|
{
|
|
|
|
|
/*
|
|
|
|
|
* ATTENTION: You do not need to implement realloc for this assignment
|
|
|
|
|
*/
|
|
|
|
|
void *oldptr = ptr;
|
|
|
|
|
void *newptr;
|
|
|
|
|
size_t copySize;
|
|
|
|
|
|
|
|
|
|
newptr = mm_malloc(size);
|
|
|
|
|
if (newptr == NULL)
|
|
|
|
|
return NULL;
|
|
|
|
|
copySize = *(size_t *)((char *)oldptr - SIZE_T_SIZE);
|
|
|
|
|
if (size < copySize)
|
|
|
|
|
copySize = size;
|
|
|
|
|
memcpy(newptr, oldptr, copySize);
|
|
|
|
|
mm_free(oldptr);
|
|
|
|
|
return newptr;
|
|
|
|
|
}
|